[libc] fix -Wmissing-braces

[nickdesaulniers]

Fixes the following errors observed on the aarch64 fullbuild:

/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/HashTable/generic/bitmask_impl.inc:116:13:
error: suggest braces around initialization of subobject
[-Werror,-Wmissing-braces]
    return {static_cast<bitmask_t>(mask_available().word ^ repeat_byte(0x80))};
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            {                                                                }
In file included from
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/search/hdestroy.cpp:10:
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/HashTable/table.h:336:41:
error: suggest braces around initialization of subobject
[-Werror,-Wmissing-braces]
  iterator end() const { return {0, 0, {0}, *this}; }
                                        ^
                                        {}

Link: https://lab.llvm.org/buildbot/#/builders/223/builds/33868/steps/6/logs/stdio
Link: #74506

[llvmbot]

@llvm/pr-subscribers-libc

Author: Nick Desaulniers (nickdesaulniers)

Changes

Fixes the following errors observed on the aarch64 fullbuild:

/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/HashTable/generic/bitmask_impl.inc:116:13:
error: suggest braces around initialization of subobject
[-Werror,-Wmissing-braces]
    return {static_cast<bitmask_t>(mask_available().word ^ repeat_byte(0x80))};
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            {                                                                }
In file included from
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/search/hdestroy.cpp:10:
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/HashTable/table.h:336:41:
error: suggest braces around initialization of subobject
[-Werror,-Wmissing-braces]
  iterator end() const { return {0, 0, {0}, *this}; }
                                        ^
                                        {}

Link: https://lab.llvm.org/buildbot/#/builders/223/builds/33868/steps/6/logs/stdio
Link: #74506

---

Full diff: https://github.com/llvm/llvm-project/pull/77345.diff

2 Files Affected:

• (modified) libc/src/__support/HashTable/generic/bitmask_impl.inc (+1-1)
• (modified) libc/src/__support/HashTable/table.h (+1-1)

diff --git a/libc/src/__support/HashTable/generic/bitmask_impl.inc b/libc/src/__support/HashTable/generic/bitmask_impl.inc
index b825cb5fbc44a8..d0cb342a60cd9c 100644
--- a/libc/src/__support/HashTable/generic/bitmask_impl.inc
+++ b/libc/src/__support/HashTable/generic/bitmask_impl.inc
@@ -113,7 +113,7 @@ struct Group {
   }
 
   LIBC_INLINE IteratableBitMask occupied() const {
-    return {static_cast<bitmask_t>(mask_available().word ^ repeat_byte(0x80))};
+    return {{static_cast<bitmask_t>(mask_available().word ^ repeat_byte(0x80))}};
   }
 };
 } // namespace internal
diff --git a/libc/src/__support/HashTable/table.h b/libc/src/__support/HashTable/table.h
index d70ca4d2338056..9b2f3beea9965e 100644
--- a/libc/src/__support/HashTable/table.h
+++ b/libc/src/__support/HashTable/table.h
@@ -333,7 +333,7 @@ struct HashTable {
     return {0, full_capacity() - available_slots,
             Group::load_aligned(&control(0)).occupied(), *this};
   }
-  iterator end() const { return {0, 0, {0}, *this}; }
+  iterator end() const { return {0, 0, {{0}}, *this}; }
 
   LIBC_INLINE ENTRY *find(const char *key) {
     uint64_t primary = oneshot_hash(key);

[nickdesaulniers]

Strangely, I haven't been able to reproduce the build bots failures when trying to cross compile a fullbuild. My cmake:

$ cmake ../runtimes -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang -G Ninja -DLLVM_ENABLE_LLD=ON -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_RUNTIMES="libc" -DLLVM_LIBC_FULL_BUILD=ON -DLIBC_HDRGEN_EXE=$HDRGEN -DLIBC_TARGET_TRIPLE=aarch64-linux-gnu

[jhuber6]

Could we construct these explicitly? It's difficult to see what it's supposed to be doing with the brace initialization.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[nickdesaulniers]

Could we construct these explicitly? It's difficult to see what it's supposed to be doing with the brace initialization.

as in

diff --git a/libc/src/__support/HashTable/table.h b/libc/src/__support/HashTable/table.h
index 9b2f3beea996..61670a5db0e3 100644
--- a/libc/src/__support/HashTable/table.h
+++ b/libc/src/__support/HashTable/table.h
@@ -333,7 +333,9 @@ public:
     return {0, full_capacity() - available_slots,
             Group::load_aligned(&control(0)).occupied(), *this};
   }
-  iterator end() const { return {0, 0, {{0}}, *this}; }
+  iterator end() const {
+    return {0, 0, IteratableBitMask{{0}}, *this};
+  }

?

[jhuber6]

Could we construct these explicitly? It's difficult to see what it's supposed to be doing with the brace initialization.

as in

diff --git a/libc/src/__support/HashTable/table.h b/libc/src/__support/HashTable/table.h
index 9b2f3beea996..61670a5db0e3 100644
--- a/libc/src/__support/HashTable/table.h
+++ b/libc/src/__support/HashTable/table.h
@@ -333,7 +333,9 @@ public:
     return {0, full_capacity() - available_slots,
             Group::load_aligned(&control(0)).occupied(), *this};
   }
-  iterator end() const { return {0, 0, {{0}}, *this}; }
+  iterator end() const {
+    return {0, 0, IteratableBitMask{{0}}, *this};
+  }

?

I meant the iterator type, but yeah. It's just a little confusing to see so many brace initializers in one place, hence the warning.

[nickdesaulniers]

I meant the iterator type,

Sorry, which of the two iterator types? The return value of end or the IteratableBitMask itself?

(When we can use c++20, designated initialization can be used to make this crystal clear).

[jhuber6]

I meant the iterator type,

Sorry, which of the two iterator types? The return value of end or the IteratableBitMask itself?

(When we can use c++20, designated initialization can be used to make this crystal clear).

We're using {0} it implicitly create the iterator type rather than iterator{0} or whatever it is. I was just confused what it's actually trying to turn those arugment into since it just looks like any other uniform initialization

[nickdesaulniers]

I meant the iterator type,

Sorry, which of the two iterator types? The return value of end or the IteratableBitMask itself?
(When we can use c++20, designated initialization can be used to make this crystal clear).

We're using {0} it implicitly create the iterator type rather than iterator{0} or whatever it is. I was just confused what it's actually trying to turn those arugment into since it just looks like any other uniform initialization

Done in a18bd3b PTAL